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<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="boost_numericconversion.converter___function_object"></a><a class="link" href="converter___function_object.html" title="converter&lt;&gt; function object">converter&lt;&gt;
    function object</a>
</h2></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.synopsis">Synopsis</a></span></dt>
<dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.template_parameters">Template
      parameters</a></span></dt>
<dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.member_functions">Member
      functions</a></span></dt>
<dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.range_checking_logic">Range
      Checking Logic</a></span></dt>
<dt><span class="section"><a href="converter___function_object.html#boost_numericconversion.converter___function_object.examples">Examples</a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_numericconversion.converter___function_object.synopsis"></a><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.synopsis" title="Synopsis">Synopsis</a>
</h3></div></div></div>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">numeric</span> <span class="special">{</span>


    <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span>
             <span class="keyword">class</span> <span class="identifier">S</span><span class="special">,</span>
             <span class="keyword">class</span> <span class="identifier">Traits</span><span class="special">,</span>          <span class="special">=</span> <span class="identifier">conversion_traits</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">,</span><span class="identifier">S</span><span class="special">&gt;</span>
             <span class="keyword">class</span> <span class="identifier">OverflowHandler</span>  <span class="special">=</span> <span class="identifier">def_overflow_handler</span><span class="special">,</span>
             <span class="keyword">class</span> <span class="identifier">Float2IntRounder</span> <span class="special">=</span> <span class="identifier">Trunc</span><span class="special">&lt;</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">source_type</span> <span class="special">&gt;,</span>
             <span class="keyword">class</span> <span class="identifier">RawConverter</span>     <span class="special">=</span> <span class="identifier">raw_converter</span><span class="special">&lt;</span><span class="identifier">Traits</span><span class="special">&gt;,</span>
             <span class="keyword">class</span> <span class="identifier">UserRangeChecker</span> <span class="special">=</span> <span class="identifier">UseInternalRangeChecker</span>
            <span class="special">&gt;</span>
    <span class="keyword">struct</span> <span class="identifier">converter</span>
    <span class="special">{</span>
        <span class="keyword">typedef</span> <span class="identifier">Traits</span> <span class="identifier">traits</span> <span class="special">;</span>

        <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">source_type</span>   <span class="identifier">source_type</span>   <span class="special">;</span>
        <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">argument_type</span> <span class="identifier">argument_type</span> <span class="special">;</span>
        <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">result_type</span>   <span class="identifier">result_type</span>   <span class="special">;</span>

        <span class="keyword">static</span> <span class="identifier">result_type</span> <span class="identifier">convert</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">;</span>

        <span class="identifier">result_type</span> <span class="keyword">operator</span><span class="special">()</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="keyword">const</span> <span class="special">;</span>

        <span class="comment">// Internal member functions:</span>

        <span class="keyword">static</span> <span class="identifier">range_check_result</span> <span class="identifier">out_of_range</span>      <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">;</span>
        <span class="keyword">static</span> <span class="keyword">void</span>               <span class="identifier">validate_range</span>    <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">;</span>
        <span class="keyword">static</span> <span class="identifier">result_type</span>        <span class="identifier">low_level_convert</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">;</span>
        <span class="keyword">static</span> <span class="identifier">source_type</span>        <span class="identifier">nearbyint</span>         <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">;</span>

    <span class="special">}</span> <span class="special">;</span>

<span class="special">}</span> <span class="special">}</span> <span class="comment">// namespace numeric, boost</span>
</pre>
<p>
        <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">converter</span><span class="special">&lt;&gt;</span></code>
        is a <a href="http://www.sgi.com/tech/stl/UnaryFunction.html" target="_top">Unary Function
        Object</a> encapsulating the code to perform a numeric conversion with
        the direction and properties specified by the Traits template parameter.
        It can optionally take some <a class="link" href="numeric_converter_policy_classes.html" title="Numeric Converter Policy Classes">policies</a>
        which can be used to customize its behavior. The <code class="computeroutput"><span class="identifier">Traits</span></code>
        parameter is not a policy but the parameter that defines the conversion.
      </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_numericconversion.converter___function_object.template_parameters"></a><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.template_parameters" title="Template parameters">Template
      parameters</a>
</h3></div></div></div>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
              </th>
<th>
              </th>
</tr></thead>
<tbody>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">T</span></code>
                </p>
              </td>
<td>
                <p>
                  The <a class="link" href="definitions.html#boost_numericconversion.definitions.numeric_types" title="Numeric Types">Numeric
                  Type</a> which is the <span class="emphasis"><em>Target</em></span> of the conversion.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">S</span></code>
                </p>
              </td>
<td>
                <p>
                  The <a class="link" href="definitions.html#boost_numericconversion.definitions.numeric_types" title="Numeric Types">Numeric
                  Type</a> which is the <span class="emphasis"><em>Source</em></span> of the conversion.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">Traits</span></code>
                </p>
              </td>
<td>
                <p>
                  This must be a conversion traits class with the interface of <a class="link" href="conversion_traits___traits_class.html" title="conversion_traits&lt;&gt; traits class"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">conversion_traits</span></code></a>
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">OverflowHandler</span></code>
                </p>
              </td>
<td>
                <p>
                  <span class="bold"><strong>Stateless Policy</strong></span> called to administrate
                  the result of the range checking.
                </p>
                <p>
                  It is a <span class="bold"><strong>Function Object</strong></span> which
                  receives the result of <code class="computeroutput"><span class="identifier">out_of_range</span><span class="special">()</span></code> and is called inside the <code class="computeroutput"><span class="identifier">validate_range</span><span class="special">()</span></code>
                  static member function exposed by the converter.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">Float2IntRounder</span></code>
                </p>
              </td>
<td>
                <p>
                  <span class="bold"><strong>Stateless Policy</strong></span> which specifies
                  the rounding mode used for float to integral conversions.
                </p>
                <p>
                  It supplies the <code class="computeroutput"><span class="identifier">nearbyint</span><span class="special">()</span></code> static member function exposed
                  by the converter.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">RawConverter</span></code>
                </p>
              </td>
<td>
                <p>
                  <span class="bold"><strong>Stateless Policy</strong></span> which is used
                  to perform the actual conversion.
                </p>
                <p>
                  It supplies the <code class="computeroutput"><span class="identifier">low_level_convert</span><span class="special">()</span></code> static member function exposed
                  by the converter.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">UserRangeChecker</span></code>
                </p>
              </td>
<td>
                <p>
                  <span class="emphasis"><em>Special and Optional</em></span> <span class="bold"><strong>Stateless
                  Policy</strong></span> which can be used to override the internal range
                  checking logic.
                </p>
                <p>
                  If given, supplies alternative code for the <code class="computeroutput"><span class="identifier">out_of_range</span><span class="special">()</span></code> and <code class="computeroutput"><span class="identifier">validate_range</span><span class="special">()</span></code> static member functions exposed
                  by the converter.
                </p>
              </td>
</tr>
</tbody>
</table></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_numericconversion.converter___function_object.member_functions"></a><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.member_functions" title="Member functions">Member
      functions</a>
</h3></div></div></div>
<div class="blockquote"><blockquote class="blockquote"><p>
          <code class="computeroutput"><span class="keyword">static</span> <span class="identifier">result_type</span>
          <span class="identifier">converter</span><span class="special">&lt;&gt;::</span><span class="identifier">convert</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span>
          <span class="special">)</span> <span class="special">;</span> <span class="comment">// throw</span> </code>
        </p></blockquote></div>
<p>
        This static member function converts an rvalue of type <code class="computeroutput"><span class="identifier">source_type</span></code>
        to an rvalue of type <code class="computeroutput"><span class="identifier">target_type</span></code>.
      </p>
<p>
        If the conversion requires it, it performs a range checking before the conversion
        and passes the result of the check to the overflow handler policy (the default
        policy throws an exception if out-of-range is detected)
      </p>
<p>
        The implementation of this function is actually built from the policies and
        is basically as follows:
      </p>
<pre class="programlisting"><span class="identifier">result_type</span> <span class="identifier">converter</span><span class="special">&lt;&gt;::</span><span class="identifier">convert</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span>
<span class="special">{</span>
    <span class="identifier">validate_range</span><span class="special">(</span><span class="identifier">s</span><span class="special">);</span> <span class="comment">// Implemented by the internal range checking logic</span>
                       <span class="comment">// (which also calls the OverflowHandler policy)</span>
                       <span class="comment">// or externally supplied by the UserRangeChecker policy.</span>

    <span class="identifier">s</span> <span class="special">=</span> <span class="identifier">nearbyint</span><span class="special">(</span><span class="identifier">s</span><span class="special">);</span> <span class="comment">// Externally supplied by the Float2IntRounder policy.</span>
                      <span class="comment">// NOTE: This is actually called only for float to int conversions.</span>

    <span class="keyword">return</span> <span class="identifier">low_level_convert</span><span class="special">(</span><span class="identifier">s</span><span class="special">);</span> <span class="comment">// Externally supplied by the RawConverter policy.</span>
<span class="special">}</span>
</pre>
<p>
        <code class="computeroutput"><span class="identifier">converter</span><span class="special">&lt;&gt;::</span><span class="keyword">operator</span><span class="special">()</span> <span class="keyword">const</span></code> just calls <code class="computeroutput"><span class="identifier">convert</span><span class="special">()</span></code>
      </p>
<p>
        <span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span>
      </p>
<div class="blockquote"><blockquote class="blockquote"><p>
          <code class="computeroutput"><span class="keyword">static</span> <span class="identifier">range_check_result</span>
          <span class="identifier">numeric_converter</span><span class="special">&lt;&gt;::</span><span class="identifier">out_of_range</span> <span class="special">(</span>
          <span class="identifier">argument_type</span> <span class="identifier">s</span>
          <span class="special">)</span> <span class="special">;</span></code>
        </p></blockquote></div>
<p>
        This <a class="link" href="converter___function_object.html#numeric_conversion_converter_internal">internal</a>
        static member function determines if the value <code class="computeroutput"><span class="identifier">s</span></code>
        can be represented by the target type without overflow.
      </p>
<p>
        It does not determine if the conversion is <span class="emphasis"><em>exact</em></span>; that
        is, it does not detect <span class="emphasis"><em>inexact</em></span> conversions, only <span class="emphasis"><em>out-of-range</em></span>
        conversions (see the <a class="link" href="definitions.html#boost_numericconversion.definitions.exact__correctly_rounded_and_out_of_range_representations" title="Exact, Correctly Rounded and Out-Of-Range Representations">Definitions</a>
        for further details).
      </p>
<p>
        The return value is of enum type <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.enum_range_check_result" title="enum range_check_result"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">range_check_result</span></code></a>
      </p>
<p>
        The actual code for the range checking logic is optimized for the combined
        properties of the source and target types. For example, a non-subranged conversion
        (i.e: <code class="computeroutput"><span class="keyword">int</span></code>-&gt;<code class="computeroutput"><span class="keyword">float</span></code>), requires no range checking, so <code class="computeroutput"><span class="identifier">out_of_range</span><span class="special">()</span></code>
        returns <code class="computeroutput"><span class="identifier">cInRange</span></code> directly.
        See the following <a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.range_checking_logic" title="Range Checking Logic">table</a>
        for more details.
      </p>
<p>
        If the user supplied a <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_userrangechecker" title="Policy UserRangeChecker">UserRangeChecker</a>
        policy, is this policy which implements this function, so the implementation
        is user defined, although it is expected to perform the same conceptual check
        and return the appropriate result.
      </p>
<p>
        <span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span>
      </p>
<div class="blockquote"><blockquote class="blockquote"><p>
          <code class="computeroutput"><span class="keyword">static</span> <span class="keyword">void</span>
          <span class="identifier">numeric_converter</span><span class="special">&lt;&gt;::</span><span class="identifier">validate_range</span> <span class="special">(</span>
          <span class="identifier">argument_type</span> <span class="identifier">s</span>
          <span class="special">)</span> <span class="special">;</span> <span class="comment">// no throw</span> </code>
        </p></blockquote></div>
<p>
        This <a class="link" href="converter___function_object.html#numeric_conversion_converter_internal">internal</a>
        static member function calls out_of_range(s), and passes the result to the
        <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_overflowhandler" title="Policy OverflowHandler">OverflowHandler</a>
        policy class.
      </p>
<p>
        For those Target/Source combinations which don't require range checking,
        this is an empty inline function.
      </p>
<p>
        If the user supplied a <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_userrangechecker" title="Policy UserRangeChecker">UserRangeChecker</a>
        policy, is this policy which implements this function, so the implementation
        is user defined, although it is expected to perform the same action as the
        default. In particular, it is expected to pass the result of the check to
        the overflow handler.
      </p>
<p>
        <span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span>
      </p>
<div class="blockquote"><blockquote class="blockquote"><p>
          <code class="computeroutput"><span class="keyword">static</span> <span class="identifier">result_type</span>
          <span class="identifier">numeric_converter</span><span class="special">&lt;&gt;::</span><span class="identifier">low_level_convert</span> <span class="special">(</span>
          <span class="identifier">argument_type</span> <span class="identifier">s</span>
          <span class="special">)</span> <span class="special">;</span></code>
        </p></blockquote></div>
<p>
        This <a class="link" href="converter___function_object.html#numeric_conversion_converter_internal">internal</a>
        static member function performs the actual conversion.
      </p>
<p>
        This function is externally supplied by the <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_rawconverter" title="Policy RawConverter">RawConverter</a>
        policy class.
      </p>
<p>
        <span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span>
      </p>
<div class="blockquote"><blockquote class="blockquote"><p>
          <code class="computeroutput"><span class="keyword">static</span> <span class="identifier">source_type</span>
          <span class="identifier">converter</span><span class="special">&lt;&gt;::</span><span class="identifier">nearbyint</span> <span class="special">(</span>
          <span class="identifier">argument_type</span> <span class="identifier">s</span>
          <span class="special">)</span> <span class="special">;</span></code>
        </p></blockquote></div>
<p>
        This <a class="link" href="converter___function_object.html#numeric_conversion_converter_internal">internal</a>
        static member function, which is <span class="underline">only used</span>
        for <code class="computeroutput"><span class="keyword">float</span></code> to <code class="computeroutput"><span class="keyword">int</span></code>
        conversions, returns an <span class="emphasis"><em>integer</em></span> value of <span class="emphasis"><em><span class="underline">floating-point type</span></em></span> according to some
        rounding direction.
      </p>
<p>
        This function is externally supplied by the <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_float2introunder" title="Policy Float2IntRounder">Float2IntRounder</a>
        policy class which encapsulates the specific rounding mode.
      </p>
<p>
        <span class="inlinemediaobject"><img src="../images/space.png" alt="space"></span>
      </p>
<a name="numeric_conversion_converter_internal"></a><h5>
<a name="boost_numericconversion.converter___function_object.member_functions.h0"></a>
        <span class="phrase"><a name="boost_numericconversion.converter___function_object.member_functions.internal_member_functions"></a></span><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.member_functions.internal_member_functions">Internal
        Member Functions</a>
      </h5>
<p>
        These static member functions build the actual conversion code used by <code class="computeroutput"><span class="identifier">convert</span><span class="special">()</span></code>.
        The user does not have to call these if calling <code class="computeroutput"><span class="identifier">convert</span><span class="special">()</span></code>, since <code class="computeroutput"><span class="identifier">convert</span><span class="special">()</span></code> calls them infernally, but they can be
        called separately for specific needs.
      </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_numericconversion.converter___function_object.range_checking_logic"></a><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.range_checking_logic" title="Range Checking Logic">Range
      Checking Logic</a>
</h3></div></div></div>
<p>
        The following table summarizes the internal range checking logic performed
        for each combination of the properties of Source and Target.
      </p>
<p>
        LowestT/HighestT denotes the highest and lowest values of the Target type,
        respectively.
      </p>
<p>
        <code class="computeroutput"><span class="identifier">S</span><span class="special">(</span><span class="identifier">n</span><span class="special">)</span></code> is short
        for <code class="computeroutput"><span class="keyword">static_cast</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;(</span><span class="identifier">n</span><span class="special">)</span></code> (<code class="computeroutput"><span class="identifier">S</span></code> denotes the Source type).
      </p>
<p>
        <code class="computeroutput"><span class="identifier">NONE</span></code> indicates that for this
        case there is no range checking.
      </p>
<pre class="programlisting"><code class="literal">
int_to_int    |--&gt; sig_to_sig     |--&gt; subranged     |--&gt; ( s &gt;= S(LowestT) ) &amp;&amp; ( s &lt;= S(HighestT) )
              |                   |--&gt; not subranged |--&gt; NONE
              |
              |--&gt; unsig_to_unsig |--&gt; subranged     |--&gt; ( s &gt;= S(LowestT) ) &amp;&amp; ( s &lt;= S(HighestT) )
              |                   |--&gt; not subranged |--&gt; NONE
              |
              |--&gt; sig_to_unsig   |--&gt; pos subranged     |--&gt; ( s &gt;= S(0) ) &amp;&amp; ( s &lt;= S(HighestT) )
              |                   |--&gt; not pos subranged |--&gt; ( s &gt;= S(0) )
              |
              |--&gt; unsig_to_sig   |--&gt; subranged     |--&gt; ( s &lt;= S(HighestT) )
              |                   |--&gt; not subranged |--&gt; NONE
</code>
<code class="literal">
int_to_float   |--&gt; NONE
</code>
<code class="literal">
float_to_int   |--&gt; round_to_zero         |--&gt; ( s &gt;  S(LowestT)-S(1)   ) &amp;&amp; ( s &lt;  S(HighestT)+S(1)   )
               |--&gt; round_to_even_nearest |--&gt; ( s &gt;= S(LowestT)-S(0.5) ) &amp;&amp; ( s &lt;  S(HighestT)+S(0.5) )
               |--&gt; round_to_infinity     |--&gt; ( s &gt;  S(LowestT)-S(1)   ) &amp;&amp; ( s &lt;= S(HighestT)        )
               |--&gt; round_to_neg_infinity |--&gt; ( s &gt;= S(LowestT)        ) &amp;&amp; ( s &lt;  S(HighestT)+S(1)   )
</code>
<code class="literal">
float_to_float |--&gt; subranged     |--&gt; ( s &gt;= S(LowestT) ) &amp;&amp; ( s &lt;= S(HighestT) )
               |--&gt; not subranged |--&gt; NONE
</code>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_numericconversion.converter___function_object.examples"></a><a class="link" href="converter___function_object.html#boost_numericconversion.converter___function_object.examples" title="Examples">Examples</a>
</h3></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">cassert</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">numeric</span><span class="special">/</span><span class="identifier">conversion</span><span class="special">/</span><span class="identifier">converter</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> <span class="special">{</span>

    <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">converter</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">double</span><span class="special">&gt;</span> <span class="identifier">Double2Int</span> <span class="special">;</span>

    <span class="keyword">int</span> <span class="identifier">x</span> <span class="special">=</span> <span class="identifier">Double2Int</span><span class="special">::</span><span class="identifier">convert</span><span class="special">(</span><span class="number">2.0</span><span class="special">);</span>
    <span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">x</span> <span class="special">==</span> <span class="number">2</span> <span class="special">);</span>

    <span class="keyword">int</span> <span class="identifier">y</span> <span class="special">=</span> <span class="identifier">Double2Int</span><span class="special">()(</span><span class="number">3.14</span><span class="special">);</span> <span class="comment">// As a function object.</span>
    <span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">y</span> <span class="special">==</span> <span class="number">3</span> <span class="special">)</span> <span class="special">;</span> <span class="comment">// The default rounding is trunc.</span>

    <span class="keyword">try</span>
    <span class="special">{</span>
        <span class="keyword">double</span> <span class="identifier">m</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">bounds</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;::</span><span class="identifier">highest</span><span class="special">();</span>
        <span class="keyword">int</span> <span class="identifier">z</span> <span class="special">=</span> <span class="identifier">Double2Int</span><span class="special">::</span><span class="identifier">convert</span><span class="special">(</span><span class="identifier">m</span><span class="special">);</span> <span class="comment">// By default throws positive_overflow()</span>
    <span class="special">}</span>
    <span class="keyword">catch</span> <span class="special">(</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">positive_overflow</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="special">)</span>
    <span class="special">{</span>
    <span class="special">}</span>

    <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
<span class="special">}</span>
</pre>
</div>
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      Luis Cacciola Carballal<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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